Strange supernovae

Most of all exploding stars of type Ia. These supernovae all have the same properties, regardless of the settings of their parent stars. Of course, we need some uniformity of the initial data — it must be binary systems consisting of a white dwarf and some other stars. But the values of the masses and the distance between the stars can vary over a wide range, and yet they will explode the same way.

 

Supernova

This consistency allows the properties of Type Ia supernova explosions as a means to measure distances in the universe. That's why it was opened by the sad fact — the accelerated expansion of the universe. Supernovae of type Ia, however, there are two dozen slightly different explosions, the features of which can be used to learn something more about the expansion of the world and, therefore, the dark energy is driving the expansion.
These failed SNe Ia, appears to occur when a white dwarf is unable to complete a supernova explosion.

"They start thermonuclear burning, but are unable to generate a blast wave, which would pass through all the star," — said George Jordan, a member of the University of Chicago. SNe Ia — just an explosion of a white dwarf star with his companion pulled enough material to start the fusion reaction. It starts by the extreme conditions on the star — its size is similar to Earth, but the weight — the star. Limit is reached the mass starts blowing the stars. These conclusions were made based on the results of computer simulations conducted on a supercomputer at the Argonne National Laboratory. All simulation took two million protsessorochasov.

Surface modeling asymmetrical white dwarf (uchicago.edu)

Surface modeling asymmetrical white dwarf (uchicago.edu)

Frustrated to discover a type Ia supernova is not so simple. Its brightness is 10-100 times less than that of a full explosion. Therefore, despite the small number of open nedovzryvov, their contribution to the total number of Type Ia supernovae is estimated at 15%. The first such star was discovered only recently — in 2002. Called SN 2002cx, this supernova is the strangest of all open. However, the most dim supernova was discovered later, in 2008. If a typical supernova can be compared with the usual 60-watt bulb, the most dull can be compared to a small part of the light provided little firefly.
The computer center of the University of Chicago to the supernova explosion has considerable experience of numerical modeling. A standard script flow explosion. It starts white dwarf thermonuclear burning in the center. It quickly spread upwards, reaching the surface of the dwarf. The release of the reaction on the surface followed by an upturn in the atmosphere of the reaction products and their movement over the surface. The meeting of two or more product streams creates shock waves that increase the reaction.

"We took the standard scenario of the explosion and learned what happens when you go to the extreme conditions," — said Jordan. As it turned out, the script failed explosion near the center of the white dwarf occurs more seats of reaction, and the resulting combustion occurs initially active. Because of a more powerful combustion star markedly expanded, gravity is unable to contain it within a small star. Because of this, the pressure and temperature increase is not enough to make a real supernova explosion occurred.

Instead of exploding, the white dwarf only on, and part of its mass is burned and released into the open space. In this scenario, resulting in the modeling process was similar to that observed properties of inferior explosion. However, the simulation also revealed a number of properties of white dwarf, which has not yet been observed by astronomers. The most interesting result was the speed of the white dwarf — in some cases, modeling its speed can be hundreds of kilometers per second. The release of the white dwarfs with such speeds have not even expected.

Sirius A and its companion - a white dwarf Sirius B (wikipedia.org)

Surface modeling asymmetrical white dwarf (uchicago.edu)

Frustrated to discover a type Ia supernova is not so simple. Its brightness is 10-100 times less than that of a full explosion. Therefore, despite the small number of open nedovzryvov, their contribution to the total number of Type Ia supernovae is estimated at 15%. The first such star was discovered only recently — in 2002. Called SN 2002cx, this supernova is the strangest of all open. However, the most dim supernova was discovered later, in 2008. If a typical supernova can be compared with the usual 60-watt bulb, the most dull can be compared to a small part of the light provided little firefly.
The computer center of the University of Chicago to the supernova explosion has considerable experience of numerical modeling. A standard script flow explosion. It starts white dwarf thermonuclear burning in the center. It quickly spread upwards, reaching the surface of the dwarf. The release of the reaction on the surface followed by an upturn in the atmosphere of the reaction products and their movement over the surface. The meeting of two or more product streams creates shock waves that increase the reaction.

"We took the standard scenario of the explosion and learned what happens when you go to the extreme conditions," — said Jordan. As it turned out, the script failed explosion near the center of the white dwarf occurs more seats of reaction, and the resulting combustion occurs initially active. Because of a more powerful combustion star markedly expanded, gravity is unable to contain it within a small star. Because of this, the pressure and temperature increase is not enough to make a real supernova explosion occurred.

Instead of exploding, the white dwarf only on, and part of its mass is burned and released into the open space. In this scenario, resulting in the modeling process was similar to that observed properties of inferior explosion. However, the simulation also revealed a number of properties of white dwarf, which has not yet been observed by astronomers. The most interesting result was the speed of the white dwarf — in some cases, modeling its speed can be hundreds of kilometers per second. The release of the white dwarfs with such speeds have not even expected.

Sirius A and its companion - a white dwarf Sirius B (wikipedia.org)

Sirius A and its companion — a white dwarf Sirius B (wikipedia.org)

Among other properties — the chemical composition of the surface, asymmetric surface properties, which is in stark contrast to the typical supernovae of type Ia. Asymmetry, in particular, is shown in the difference between what we can see, depending on the viewing angle binary system with the earth (or Space Telescope). The same asymmetry leads to faster white dwarf receiving in one direction much more push than others. This push can be strong enough to throw the dwarf from the binary system. In the future such ultrafast stars may even leave the galaxy, and freed from its gravitational pull. If the push force is insufficient to break the connection between the two stars, the orbit of the white dwarf is on average lower and silnoelliptichnoy, while most of the white dwarfs in low orbits have a very small eccentricity.

The chemical composition of the surface of a failed supernova is heavier composition of normal white dwarf. A typical white dwarf is composed almost entirely of carbon and oxygen, while the simulation failed to blast the surface composition were added calcium, titanium and iron. Because there is no supernova explosion swept the outer space elements formed in fusion reactions, most of the star ejected material falls back to the surface, which brings heavy elements and provokes them further synthesis. White dwarfs with such properties has not been found yet, however, there are stars, strangeness, which can be explained by the results of a new simulation. However, a full evaluation of simulation yet.

 

Cosmos Magazine
On materials of the University of Chicago

Category: Astronomy and Space

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